For tens of thousands of years,
Homo sapiens lived throughout Africa,
but only some of these people were our ancestors.
By 60,000 years ago, our ancestors were on the move,
and their expansions started to have staying power,
we don't know how fast, or how far they traveled.
Today, hunter-gatherer groups move, on average, about 1 km a year,
it's about half mile.
But it's not always consistent--what we do know is this,
as their descendants moved into new environments,
they became more isolated from one another,
setting the stage for the high level of genetic diversity
that we see in Africa today.
By 50,000 years ago, people started making more sophisticated tools,
and creating a lot more art.
Did new language abilities spark this burst of innovation?
Maybe a genetic change in a population allowed some people
to express more complex concepts through language,
and so to out-compete those who couldn't,
no one really knows.
Around 50,000 years ago, small groups of travelers crossed into Asia,
possibly as few as a hundred people in all.
Everyone alive today who has any non-African ancestors is probably descended from these travelers.
Within a few thousand years, climatic conditions became drier,
and the Sahara desert expanded, making it harder to turn back,
the intrepid travelers and their descendants followed a coastal route, eastward in Asia,
reaching present day Malaysia within a few millenium.
Did they meet Homo erectus along the way?
By 45,000 years ago, people were living in parts of Australia and making their mark.
In order to get there, they had to cross the 90 km--that's about 50 miles--of open water
which separates Australia from the nearest islands of present-day Indonesia.
Just how this was done, no one knows.
It's amazing to think that people reached Australia and Europe
at around the same time.
Traveling eastward and southward along the coast of Asia,
people didn't experience big and hard environmental changes;
but hitting northward, into Europe,
they faced extremely harsh, cold climates and tough terrain.
As humans moved into Europe, they also ran into the Neanderthals,
who'd been living there for hundreds of thousands of years.
The Neanderthals were stocky, and physically better adapted to the cold climates,
but the newcomers proved to be very skilled
at shaping natural materials into useful and attractive objects.
Though the Neanderthals may have acquired some of their neighbors' advanced technologies,
they soon found it hard to keep up.
Humans' success might have meant the Neanderthals' downfall.
The two populations coexisted, even interbred, for a few millenium,
but by 35,000 years ago, Neanderthals were confined
to the southwest corner of Europe, and soon thereafter, they had disappeared,
another unsolved mystery, yes, our story is full of them.
Homo sapiens outlasted their cousins, and expanded their reach
across Africa, Eurasia, and Australia;
but soon times got tough for everyone,
how would our ancestors cope with the extreme temperatures of the ice age.